A spinal tap is a procedure which takes samples of a patient's cerebrospinal fluid (“CSF”). Spinal taps are performed when the physician suspects that the patient may have increased intracranial pressure (such as in pseudotumor cerebri) or an infection of the central nervous system (such as meningitis or encephalitis). These procedures are often performed in the emergency room but are also performed in a doctor's office or in a hospital setting.
Usually, before beginning a spinal tap procedure, the physician, or another medical professional arranges the contents of a spinal tap “kit” on a tray, positioned next to where the physician will be sitting to perform the procedure. The “kit” usually consists of four sterile tubes, a spinal needle (with a stylet inserted through the spinal needle), along with items for sterilizing the patient's skin, draping the patient, and measuring the intracranial pressure. Sometimes a test tube rack to hold the tubes is also built into the tray. Before the procedure, the physician or another medical professional removes all of these items from their sterile packaging, and arranges everything on the tray for easy access during the procedure.
Usually, the patient is asked to lie down on his or her side in a curled-up position, exposing the back. The physician then cleans and may numb the skin around the insertion point of the spinal needle. The physician then inserts a spinal needle, with a stylet inside the spinal needle, between the patient's vertebrae (usually in the L3-4 or L4-5 interspace) and advances the needle until the needle has reached the fluid-filled area surrounding the patient's spinal cord (commonly referred to as the dural space). The stylet is commonly used to prevent the tip of the spinal needle from becoming blocked by tissue as the needle is inserted through the patient's skin and other tissues, but some physicians prefer not to use the stylet. Once the needle is in place, the stylet is removed from the spinal needle. CSF flows through the needle and drips from the proximal end of the needle, which is known as the “hub” of the needle. The CSF is collected in the first test tube by holding it beneath the proximal end of the spinal needle. Once the desired amount of CSF (approximately 1 ml (or 1 cc) of CSF) is collected in the first test tube, the first test tube is set aside and a second test tube is held beneath the proximal end of the spinal needle to continue collection of the CSF as it drips from the proximal end of the spinal needle. The process is repeated until the desired amount of CSF is collected in the tubes.
Once collected; CSF is then sent to a laboratory to determine if the patient is suffering from viral (for example, Enteroviruses and Herpes viruses, as well as Arboviruses, Rabies or measles among other viral agents), bacterial (including Haemophilus influenza, Streptococcus pneumoniae, Neisseria meningitidis, and also Listeria monocytogenes, Staphylococcus aureus, Mycobacterium tuberculosis, Escherichia coli or other Gram negative enteric bacteria) or fungal (including Cryptococcus neoformans, Coccidioides immiitis, among other fungal agents) infection of the brain or supporting structures, among other possible diagnoses. The CSF is also examined for white and red blood counts and chemical components. The CSF can also be evaluated for the presence and amount of specific proteins, which may aid in the diagnosis of non-infectious nervous system ailments, such as Multiple Sclerosis.
The present procedure suffers from several drawbacks.
First, because of the difficulty in maintaining the collection tube under the proximal end of the spinal needle and the unpredictable nature of dripping fluids, CSF droplets are sometimes missed, or they run down the outside of the collection tube instead of into the collection tube.
Second, the proximal end of spinal needles typically includes a hub (e.g., a LUER-LOK™ hub). The CSF collects in the hub before forming droplets, and this mass of fluid in the spinal needle hub exacerbates the unpredictability of CSF drop formation and represents a volume of CSF that is not collected.
The procedure can be made more difficult if a patient is unable to remain calm or still, which is common when the patient is very young or very sick. In such cases the patient may need to be restrained, sedated, or both. Increasing the efficiency of CSF collection may reduce the duration of this procedure, which, in turn, may reduce the duration of time that the patient is restrained or given potentially dangerous sedative medications.
The CSF collection procedure also represents significant risk to the patient. Patients may develop severe side effects from the loss of too much CSF, including severe headaches. Increasing the efficiency of CSF collection may reduce the risks associated with excessive loss of CSF.
The risk of the patient moving and causing injury exists for the duration of the procedure. These risks include a risk of lacerating a spinal nerve, lacerating the meninges (causing permanent or persistent leaks of CSF) or bleeding, which complicates the Interpretation of laboratory results. These risks are increased in very young patients who are more likely to move during the procedure. Increasing the efficiency of CSF collection may reduce the duration of the procedure, which, in turn, would reduce these risks.
Failure to collect adequate amounts of CSF can result in a misdiagnosis or an absence of a definitive diagnosis. In the absence of a definitive diagnosis, the patient may not receive necessary treatment, may be subjected to inappropriate treatment, or may be treated in a manner which subjects the patient to a wide variety of medications to cover a broad range of potential ailments or infecting organisms. If mistreated, the patient's illness may worsen. Otherwise, the patient may be subjected to the potentially life threatening side effects of a broad range of treatments. Increasing the efficiency of CSF collection may aid in obtaining the correct diagnosis, which may reduce these risks.
For at least these reasons, there is a continuing need for methods and devices for collecting body fluids, in particular CSF, and the present invention satisfies this need.